S3000 and S4000 PLC’s

The S3000 and S4000 controllers are identical in terms of basic operation. The primary difference is the S4000 has more on board inputs/outputs available.

Normal operation:

1. RTU light will be ON, steady green

2. The 13.8 VDC light will be ON

3. If running on line power, the 24 VAC light will be ON

4. If powered by solar panel, the SDR light will be on, 24 VAC light will be OFF

5. You will see lights flashing on communication ports

6. LCD display will show normal information

7. No alarms from the RTU

Troubleshooting:

NOTE- The green RTU light flashing mostly likely indicates a faulty personality module. This may include frozen data or garbage characters on the LCD display. This can cause the RTU to give a Loss of Signal indication. Corrective measure- replace personality module. If replacing the personality module does not correct the problem, replace the S3000/S4000 controller using the newer personality module.

Loss of Signal may be caused by faulty personality module as indicated above. Other common causes of Loss of Signal can include faulty antenna and coax; faulty radio patch cord or lightning arrestor; antenna direction changed due to wind; faulty power supply; faulty radio or no incoming power to the RTU unit. Click the links within the text above to learn more how to test/check these items.

Erratic/incorrect pressure or level readings can be an indication of a faulty pressure transmitter (transducer). If the pressure transducer tests good, other problems could be caused by faulty transducer cable/wiring or supply to transducer is blocked. If these test normal, it is possible the input to the S3000/S4000 is faulty- replace the S3000/S4000 controller.

Erratic/incorrect flow readings can be caused by a faulty flow meter or problem with wiring/cable go to the flow meter. There are two typical signals used for flow meters- 4-20 milliamp OR pulse type. 4-20 mA flow meters will be connected to an analog input in the lower left corner terminal strip on the controller. Testing of 4-20mA signal will be done with a voltmeter set to read current in milliamps. 4 milliamps is zero flow, 20 milliamps is the max rated flow output for that meter. For pulse type output flow meters, it typically will be connected to the PI1 or PI2 terminal on the lower right side of the M1500. During normal operation the corresponding light next to the input will be flashing when a pulse signal is coming from the flow meter. If the light is not flashing while there is flow going through the meter, this indicates a problem either with cabling/wiring or the meter itself. Reading the signal from a pulse type flow meter requires a voltmeter that has the capability of measuring frequency (hertz).

Pump or valve fail alarms are typically caused when the system calls on the pump or valve and a run indication does not come back from the pump or valve. Under normal conditions, for example, pump 1 will be connected to the DO1 output on the controller. When the system calls pump 1, the DO1 light will come on, and closes a dry contact in the S3000/S4000 to complete the circuit and call the pump on. Likewise, the motor control center, upon successfully turning the pump on, will close a contact that is wired to DI1 for a run back indication. The DI1 light will come on, indicating a run condition for the controller.

Any time there is a pump/valve fail alarm, it will be because this sequence was not completed.

If the DO1 light does not come on, the problem will be on the Micro-Comm side of the system. If it does come on but the pump does not start, then the problem most likely lies in the wiring to the motor control center or within the motor control center itself. If the DI1 light (run back) does not come on when the pump is running, then the problem is most likely in the motor control center or wiring to it. If the DI1 light does come on, but you still get a pump fail alarm, the problem will be on the Micro-Comm side of the system is and is most likely a faulty S3000/S4000 controller. Drawings for the RTU supplied by Micro-Comm show which connections are used for inputs and outputs for pumps and valves.

Quick reference for pump/valve fails:

Output light won’t come on = problem on Micro-Comm side of system

Output light comes on but pump won’t start = problem on motor control center side

Input light won’t come on = problem on the motor control center side

Input light does come on = problem on Micro-Comm side of system

Backup battery is typically a 12 volt, 12 amp hour gel cell type. The battery is constantly charged by the internal power supply. When line power goes off, the system automatically switches to the battery. When power comes back on, the system automatically switches back to line power. Common problems are usually related to a faulty battery. Inspect battery for cracks, bulges, and corroded terminals- if found, replace it. To test, turn off breaker (line power) and see that the RTU continues to run on battery power. The time it will run on battery power is dependent on age of battery and amount of current draw on the RTU which is mostly dependent on how often the radio transmits.

Other items sometimes used with an S3000/S4000 controller:

A radio switch (model L54) is used when there is more than one radio in the enclosure. The radio switch has four lights that come on in sequence as the PLC communicates with the rest of the system. Watch the lights for at least a few minutes to insure that the lights change periodically. If the radio switch is defective you may not see the lights change, and there will often be Loss of Signal alarms as well.

Discrete Input or output expansion modules work basically the same as the inputs and outputs on the controller itself. Both have lights that come on when the input or output is activated. Use the same troubleshooting logic as listed above for the controller.

Communication ports:

Typically, COMM 1 is used for radio communications. Two very important lights associated with COMM 1 are the TXD and RXD lights. When you hear telemetry sounds on the radio, you will see the RXD light flash in conjunction with the sound you hear. This means that data is coming from the radio, through the radio cable and into the RTU controller.

The TXD light will come on when the RTU transmits data out through the radio. Note the radio will be silent when it transmits. You will see the transmit light on the front of the radio come on in conjunction with the TXD light on the controller.

During normal operation you will see the RXD light flashing frequently. You will see the TXD light come on for about a second or so every few minutes, depending on the polling time of the system. In some cases, you may see the TXD light come on more frequently if the RTU is being used as a radio relay for other sites in the system.

Failure to see activity on the RXD light when you hear sound on the radio could be faulty radio or radio cable. Failure to hear any sounds on the radio could indicate a faulty radio or a problem with the antenna system.

If the RXD light is behaving normally but you never see a TXD light could indicate a bad personality module or the RTU controller (example S3000) itself.

COMM 2 is typically used for communicating with the LCD keypad and display. Under normal circumstances you will see ongoing activity with the TXD and RXD lights on COMM 2.

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